This invention relates to a process for desulfurization of ores, particularly coal, that is continuous and which recovers a high grade sulfur crystal.
A primary use of the process is for production of a sulfurless coal powder than can be fired in powder form, or further processed into briquettes by conventional means. The crystaline sulfur is suitable for general sulfur products or in continuous steps may be melted and cast into construction blocks. This process is adaptable to other ores for recovery of tungsten, cinabar, etc. which are relatively high in sulfur content.
The critical need and dependence on fossil fuels, particularly oil, has caused a reevaluation of fuel use priorities. It is requisite to examine the specific type of fuel to be consumed in each instance. Because oil and its refined products are a convenient source of power for vehicles, it is desirable to reserve the limited oil resources to such uses if it is to be used as a power source. Ideally oil should not be consumed as a power source but reserved for lubricants and other by-products such as solvents and plastics.
Natural gas similarly should not be used either as a power source or for heating. Because of its particularly clean burning, natural gas should be reserved for open flame uses such as cooking and other clean combustion applications.
Stationary power sources are ideally suited for burning of coal which is available in abundance in certain geographical areas and particularly throughout North America. However, much of the available coal is contaminated with sulfur, which generates a noxious pollutant when the coal is combusted. Expensive pollution control devices installed to wash the combustion gases are only partially successful in removing sulfur, sulfur compounds and oxidants before releasing such combustion gases to the atmosphere. Consequently, much of the coal mined that is not of low sulfur content or is otherwise highly contaminated with impurities is simply left in gob piles.
Ideally, the sulfur contaminant should be removed prior to combustion. Past processes are of limited efficiency and contribute excessively to the cost of coal as a common fuel.
The process devised is economical and is operable as a continuous rather than batch method. Furthermore, the process recovers and recycles the solvent used to separate sulfur from the ore maintaining solvent losses at a minimum. The large quantities of sulfur recovered are usable in a coupled process stage to produce building blocks at a cost competitive with similar concrete blocks. The process is particularly applicable to gob pile coal that has been abandoned and exists in huge quantities. Other features of this process are described in greater detail in the detailed description of the preferred embodiment hereinafter.